DC Bus Bar Structure with Segmented Insulation for Low Inductance
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Solution Overview
Problem
In power converters, reducing inductance while ensuring high insulation reliability between positive and negative electrodes of a DC bus bar becomes challenging as the interval between electrodes is minimized, leading to defects like through holes and short circuits.
Innovation Solution
A bus bar structure with a first and second insulating member, where an insulating sheet different from these members is sandwiched between them, and a projecting structural member ensures minimal distance and high insulation reliability, using materials like laminated PET for the insulating sheet and metal for structural members to prevent sink marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the interval between positive and negative electrodes is shortened to reduce inductance, then conversion efficiency is improved, but insulation reliability deteriorates due to resin defects like through holes
Solution Approach 1:
The insulation structure is segmented into multiple independent layers: a first insulating member (resin) fixing the first bus bar, a second insulating member (resin) fixing the second bus bar, and a thin insulating sheet positioned between them. This segmentation allows each layer to perform its insulation function independently, preventing through-hole defects from compromising overall insulation reliability while maintaining short electrode intervals for low inductance.
Solution Approach 2:
A thin insulating sheet acts as an intermediary element positioned between the first and second bus bars. This intermediary layer provides additional insulation protection at the critical interface where high voltage stress occurs, preventing direct contact and electrical breakdown between opposite polarity bus bars even when the overall interval is minimized for low inductance.
2Volume of moving object
If the interval between positive and negative electrodes is further shortened for miniaturization, then device size is reduced, but manufacturing precision deteriorates due to increased risk of through hole defects
Solution Approach 1:
The insulation system is divided into multiple layers with the thin insulating sheet specifically positioned to prevent through-hole defects. This segmentation allows the manufacturing process to address insulation integrity at the critical interface separately from the overall structure, enabling miniaturization without sacrificing manufacturing precision.
Solution Approach 2:
The thin insulating sheet is pre-positioned between the bus bars before final assembly, providing beforehand cushioning against potential through-hole defects. This preventive measure ensures that even if resin casting defects occur, the insulation reliability is maintained, enabling aggressive miniaturization with controlled manufacturing risk.
3Reliability
If resin is cast into the interval between bus bars to ensure insulation, then insulation is provided, but defects like through holes occur when the interval is further shortened
Solution Approach 1:
The thin insulating sheet serves as an intermediary that eliminates the need for relying solely on resin casting for insulation. By positioning this dedicated insulating layer between the bus bars, the system provides reliable insulation without subjecting the resin to the high-stress conditions that cause through-hole defects in minimized intervals.
Solution Approach 2:
The insulation function is extracted from the resin casting process and assigned to a dedicated thin insulating sheet. This extraction allows the resin to focus on its primary functions of fixing the bus bars and filling gaps, while the thin sheet specifically handles the insulation task, preventing the formation of through-hole defects.
Data Source
AI summary
Inductance is reduced while high insulation reliability between positive and negative electrodes of a DC bus bar is ensured. The DC bus bar 801a (801b) is held; the bus bar 801a (801b) is fixed by an insulating member 802a (802b) having an insulating property, with one surface 14 (15) of the bus bar 801a (801b) exposed; the bus bar 801a is arranged such that the surface 14 of the bus bar 801a faces the surface 15 of the second bus bar 801b; an insulating sheet 803 is held between the bus bar 801a and the bus bar 801b; the first insulating member 802a has a projecting part 804a projecting toward the second insulating member 802b; and the projecting part 804a has, at an end part thereof, an abutting surface 13 in contact with the second insulating member 802b.